GUM-RESINS 



753 



Gum tragacanih is gathered, about the end of June, from the Astragalus tragacantha 

 of Crete and the surrounding islands. It has the appearance of twisted ribands ; is 

 white or reddish; nearly opaque, and a little ductile. It is difficult to pulverise, 

 without heating the mortar. Its specific gravity is 1*384. When plunged in water, 

 it dissolves in part, swells considerably, and forms a very thick mucilage. 100 parts 

 of it consist of 53*30 arabine ; 33*30 bassorine and starch; 11*0 water; and from 

 2 to 3 parts of saline matters. It is employed in calico-printing, and by shoe- 

 makers. 



Gicm of Bassora. See BASSORINE. 



Gum of seeds, as linseed, consists of 5270 afabine ; 28*9 of an insoluble mattet ; 

 10-3 water; and 7*11 saline matter. Neither bassorine nor cerasine seems to be pre- 

 sent in seeds and roots. 



GUM, BRITISH. See DEXTBINE. 



GUM ELASTIC. See CAOUTCHOUC. 



GUM I.AC. See LAC. 



GUM-RESINS. (Gomme-resincs, Fr.; Schleimharze, Ger.) When incisions are 

 made in the stems, branches, and roots of certain plants, a milky juice exudes, which 

 gradually hardens in the air ; and appears to be formed of resin and essential oil, held 

 suspended in water charged with gum, and sometimes with other vegetable matters, 

 such as caoutchouc, bassorine, starch, wax, and several saline matters. The said con- 

 crete juice is called a gum-resin ; an improper name', as it gives a false idea of the 

 nature of the substance. They are all solid ; heavier than water ; in general opaque 

 and brittle; may have an acrid taste, and a strong smell ; their colour is very vari- 

 able. They are partially soluble in water, mostly soluble in alcohol ; and the solu- 

 tion in the former liquid seldom becomes transparent. Many of the gum-resins are 

 medicinal substances, and but little employed in the arts and manufactures. The fol- 

 lowing is a list of such : assafoetida ; gum ammoniac; bdellium; euphorbium; gal- 

 banum ; gamboge ; myrrh ; olibanum or frankincense ; opoponax ; and scammony. The 

 gum-resins which are employed in the arts or manufactures are described in this work 

 Under their peculiar names. 



The following Tables give our importations of Gum and Gum-Kens from 1868 to 

 1870 : 



VOL. II. 



3C 



